Rail flaw detector mechanism



Oct. 18, 1938. H. c. DRAKE RAIL FLAW DETECTOR MECHANISM Filed March 12, 1955 IIIII} M L'Snnentor Harcourt C.Drake 8g /V W I Gttomeg Patented Oet.18, 1938 I 2,133,687

UNITED STATES PATENT OFFICE RAIL FLAW DETECTOR MECHANISM Harcourt C. Drake, Hempstead, N. Y., minor to Sperry Products, 1110., Brooklyn, N. Y., a corporation of New York Application March 12, 1935, Serial No. 10,645 10 Claims. (01. 175-183) This invention relates to rail flaw detector distance beyond the surface defect. It has been mechanisms of the type employed in the Sperry discovered that frequently internal fissures exist rail flaw detector cars. The general principle close to the surface defect but such internal underlying the operation of these cars is well fissures cannot be detected because the paint known and consists in energizing the rail by mark which originates at the surface defect is 5 passing current therethrough to establish an prolonged in extent by the amplifier characterelectromagnetic field surrounding the same and istics so that it covers the succeeding portionof then exploring said field for irregularities caused the rail in which a real internal defect exists. by the presence of flaws within the rail. Such It is the principal function of this invention to irregularities are detected by inductive means provide a remedy for the situation described 10 which generate an E. M. F. which after being above whereby the impulse passing through the suitably amplified is caused to operate a recorder amplifier is limited in extent so that paint marks pen on a chart and at the same time discharge will be placed only immediately adjacent the inpaint on the rail at the point oi flaw. ternal fissure, or if the paint mark is made at The E. M. F. which is generated by the induca surface defect such paint mark will not ex- 15 tive coil passing through the region of flaw is tend beyond the region of the surface defect. small and must be amplified by a thermionic Further objects and advantages of this invenamplifier in order to give an output capable of tion will become apparent in the following deperforming the functions stated above, namely, tailed description thereof.

operating pens and rail marking means. It will In the accompanying drawing, 20 be understood thatthe region of magnetic dis- Fig. 1 is a side elevation of a portion of a tortion caused by the presence of a flaw is very Sperry rail fiaw detector car. small in extent and since the car is travelling Fig. 2 is a wiring diagram illustrating the prinpast said region at substantial speed the total ciple embodied in this invention.

26 time during which the inductive detector means Referring to Fig. l of the drawing, there is will be affected by the flaw is very small and disclosed a portion of a Sperry rail flaw detector therefore the duration of the generated E. M. F. car comprising the car body l0 within which will also be small. For this purpose the charis mounted a generator G adapted to supply curacteristics of the amplifier are made such that rent to the rail to establish an electromagnetic 80 the impulse which is put into the amplifier is field surrounding the same. The current from 30 prolonged in duration as by inserting a congenerator G may be passed into and out of the denser of large capacity in the amplifier circuit rail by means of sets of brushes H and I2 carwith a large resistance leak across the same so -ried by a current brush carriage i5, said carthat the charge is held fora substantial time. riage being supported from the car body In by One of the difiiculties experienced in rail flaw means such as cables l6 and springs, not shown, 35 testing is that surface indications such as burns which normally maintain the current brush caron the rail surface caused by slipping of driver riage in raised or ineffective position. When it wheels cause a distortion of the electromagnetic is desired to lower such carriage into engagefield which is picked up by the detector means ment with the rail, fluid pressure such as com- 0 and results in a pen mark on the chart and a pressed air is supplied to cylinders I! to depress paint mark on the rail in the same manner as pistons [8 operating therein, said pistons being an internal fissure. Operators have been trained connected to the current brush carriage so that to detect such surface indications from their said carriage is lowered against the action of the position at the rear of the detector car and such retractile springs. The current brush carriage marks are therefore not investigated. However, may be adapted to ride along the rail on means 45 because of the characteristics of the amplifier such as flanged wheels l8. which have been described above which prolong The electromagnetic field surrounding the rail the period of an impulse caused by the distoris uniform as long as there are no flaws. When tion of the magnetic field, it so happens that a fiaws occur there is a distortion of the electropaint mark which is caused byasurface defectwill magnetic field in the region of the fiaw and such 50 extend for a distance which may be six or eight distortions are designed to be detected by ininches beyond the surface defect. In other words, ductlon means which may comprise a pair of the'impulse generated by the surface defect is opposed induction coils 20 supported in a housof short duration but because the amplifier proing 2|, carried by a detector carriage 22 which as longs this period the paint mark extends for a is designed to be supported on the current brush carriage for movement independent thereof by means such as loose-fitting bolts 23 and springs 24 constituting limited universal joints. The detectorlcarriage 22 may be supported on the rail surface by means such as rollers 25. It will now be seen that as the car travels along the rail R the inductive means 20 are maintained a constant distance above the rail surface and will normally cut a constant number of lines of force. When a region of flaw is encountered one of the coils will cut a difierent number of lines of force and there will be generated a differential E. M. F. which after being amplified by an amplifier may be caused to operate indicating means such as pens operating on a moving chart and rail-marking means' such as a paint gun.

Referring to Fig. 2, it will be seen that the detector unit is arranged to impress the difierential E. M. F. on the amplifier, which may be an ordinary cascade type of resistance coupled amplifier. The duration of the impulse into the amplifier is prolonged by means such as a large capacity condenser C and high resistance S, so that the charge placed upon C'will slowly leak off the high resistance. The output of the amplifier is shown as energizing a magnet which closes the circuit through a pen magnet 3| which actuates pen P. At the same time that the pen magnet 3| is energized, there is also energized a paint-gun magnet which controls the energizationof a paint gun by actuating a valve-stem 4| therein so that the paint gun is operated to discharge paint on the rail. The paint gun is mounted as shown in Fig. 1 so as to compensate for the travel of the car and for the lag in operation of the gun whereby a paint mark is obtained at the region of magnetic distortion caused by a fiaw or surface defect.

As stated in the introduction to this specification, it is desirable for the reasons therein set forth to limit the duration of the output to such an extent that the output from the amplifier will cease as soon as the pens and the paint magnet have been energized.

For this purpose we have placed in the circuit controlled by the output of the amplifier an additional magnet of slightly greater strength than the magnet 30 and the paint magnet so that said additional magnet will be energized only after the pen mag-net and the paint magnet have been energized. Said additional magnet controls an auxiliary circuit which is normally open and adapted to be closed at a set of contacts 46 when the additional magnet is energized. Said auxiliary circuit short-circuits the condenser C to cause the same to discharge quickly instead of d scharging slowly by way of the large resistance S. As a result, there is obtained a limitation of the output of the amplifier, said limitation becoming effective immediately after the pens and the paint gun have been energized.

, In accordance with the provisions of the patent statutes, I have herein described the principle and operation of my invention, together with the apparatus which I now consider to represent the best embodiment thereof, but I desire to have it understood that the apparatus shown is only illustrative and that the invention can be carried out by other equivalent means. Also, while it is designed to use the various features and elements in the combination and relations described, some of these may be altered and others omitted without interfering with the more general results outlined, and the invention ex tends to such use.

Having described my invention, what I claim and desire to secure by Letters Patent is: g

1. In a rail flaw responsive mechanism having means which responds to flaw by generating an electrical impulse of relatively short duration, an amplifier for amplifying said impulse, said amplifier having means for prolonging the duration of said impulse and indicating means actuated by the output of said amplifier, means for limiting the actuation of said indicating means, said last-named means including means for rendering said prolonging means ineffective.

2. In a rail flaw responsive mechanism having means which responds to flaw by generating an electrical impulse of relatively short duration, an amplifier for amplifying said impulse, said amplifier having means for prolonging the dura-.

tion of said impulse and indicating means actuated by the output of said amplifier, means for limiting the actuation of said indicating means, said last-named means including means controlled by the output of' said amplifier for limiting the duration of said output.

3. In a rail flaw responsive mechanism having means which responds to flaw by generating an electrical impulse of relatively short duration, an amplifier for amplifying said impulse, said amplifier having means for prolonging the duration of said impulse and indicating means actuated by the output of said amplifier, means for limiting the actuation of said indicating means, said last-named means including means controlled by the output of said amplifier for rendering said prolonging means ineffective.

4. In a rail flaw responsive mechanism having means which responds to fiaw by generating an electrical impulse of relatively short duration, an amplifier for amplifying said impulse, said amplifier having means for prolonging the duration of said impulse and indicating means actuated by the output of said amplifier, means for limiting the actuation of said indicating means, said last-named means including means controlled by a predetermined output of said ampliizier for rendering said prolonging means ineffec- 5. In a rail flaw responsive mechanism having means which responds to flaw by generating an electrical impulse of relatively short duration, an amplifier for amplifying said impulse, said amplifier having means for prolonging the duration of said impulse and indicating means actuated by the output of said amplifier, means for limiting the actuation. of said indicating means, said last-named means including means, adapted to be rendered effective when the output of said amplifier is sufficient to actuate said indicating means, for rendering said prolonging means ineffective. 7

6. In a rail flaw responsive mechanism having means which responds to fiaw by generating an electrical impulse of relatively short duration, an amplifier for amplifying said impulse, said amplifier having means including a condenser of large capacity and a high resistance leak therefor whereby the duration of said pulse is prolonged and indicating means actuated by the output of said amplifier, means for limiting the actuation of said indicating means, saidlast-named means including means for rendering said condenser ineffective.

7. In a rail flaw responsive mechanism having means which responds to flaw by generating an" electrical impulse of relatively short duration, an amplifier for amplifying said impulse, said amplifier having means including a condenser of large capacity and a high resistance leak therean electrical impulse of relatively short duration,

an amplifier for amplifying said impulse, said amplifier having means including a condenser of large capacity and a high resistance leak therefor whereby the duration of said pulse is prolonged, and indicating means actuated by the outpt oi said amplifier, means for limiting the actuation of said indicating means, said lastnamed means including means controlled by the output of said amplifier for short-circuiting said condenser.

9. In a rail fiaw responsive mechanism having means which responds to fiaw by generating an electrical impulse oi relatively short duration, an amplifier for amplifying said impulse, said amplifier having means including a condenser of large capacity and a high resistance leak therefor whereby the duration of said pulse is prolonged and indicating means actuated by the output of said amplifier, means for limiting the actuation of said indicating means, said lastnamed means including means controlled by a predetermined output of said amplifier for short- 7 circuiting said condenser.

10. In a rail fiaw responsive mechanism having means which responds to fiaw by generating an electrical impulse of relatively short duration, an amplifier for amplifying said impulse, said amplifier having means including a condenser of large capacity and a high resistance leak therefor whereby the duration oi said pulse is prolonged and indicating means actuated by the output 0! said amplifier, means for limiting the actuation of said indicating means, said last-named means including means adapted to be rendered eiiective when the output 0! said amplifier is sume cient to actuate said indicating means for shortcircuiting said condenser.

HARCOURT C. DRAKE. 

